Urosolenia yalongii Kociolek & Liu, 2016

Liu, Yan, Kociolek, J. P. & Fan, Yawen, 2016, Urosolenia and Acanthoceras species from Hainan Province, China, Phytotaxa 244 (2), pp. 161-173 : 163-165

Urosolenia yalongii Kociolek & Liu , sp. nov. ( Figs 1–18 )

LM: frustules solitary, subcylindrical. Valve asymmetrical, conical, forming a long tubular extension. Apical axis of the frustule slightly offset from the pervalvar axis. Total frustule length: 143–181 μm, pervalvar length: 60–91 μm, width 6–12 μm, extension length: 41–73 μm, girdle band density: 4–5 per 10 μm. SEM: valve areolae round, small, 5–6 per 1 μm, with numerous poroids located irregularly ( Figs 13, 17 ) and extending to the base of the extension. Poroids large, round to elongated. Rib-like structures lacking between the poroids. Girdle band width: 2–3 μm, with small, open, slit-like areolae ( Fig. 11 ), areolae arranged nearly regularly, 11–13 rows per band, 6–7 rows per 1 μm. Round poroids distributed randomly on the bands ( Fig. 17 ). Imbrication line visible, bands joined together with a siliceous ridge internally ( Fig. 11 ). Ending of the extension sharply pointed with 3–5 teeth ( Figs 14, 15, 16, 18 ).

Type:— CHINA. Hainan Province: Orchid valley, unnamed stream, in sediments, Y. Liu & L. Li, 14 February 2012 (holotype: HANU!, individual in slide THGZ 2012015, here illustrated as Fig. 1 , isotype: COLO! JPK material no. 12HN15).

Etymology: —This species is named for the type locality.

Remarks: —Based on the outline, our species appears very similar to U. longiseta ( Zacharias 1893: 38) Edlund & Stoermer (1993: 59) , but the latter species has larger frustules and longer extensions ( Tremarin et al. 2015). It also has very long setae at the tip of the extension compared with the 3–5 teeth in our species. Urosolenia yalongii also resembles U. amazonica Sala, Núñez-Avellaneda & Vouilloud (2008: 163) and U. delicatissima based on valve outline and dimensions. Urosoleina amazonica has 4–6 small teeth at the tip of the extension, denser bands per 10 μm and a valvocopula with a serrated interior edge ( Sala et al. 2008). A diatom that resembles Urosolenia eriensis ( Smith 1872: 44) Round & Crawford in Round et al. (1990: 324; they do not specify the taxon illustrated) looks similar, and it has also a few small teeth at the end of extensions ( Round et al. 1990, p. 325, fig. g). However, the frustule is smaller, the band density is coarser and, according to Round et al. (1990), no poroids were observed on the valve and the areolae on the copulae are round, small and irregularly arranged (p. 325, fig. d). These differences support the recognition of these species as separate. Urosolenia delicatissima differs from ours by the long setae, the two small teeth on the tip of the extension, the buttonhole shaped holes with external openings on the valve, and the denser areolae on the band ( Sala et al. 2008).

Figures

FIGURES 1–9: Urosolenia yalongii, LM. Type material from Yalong valley forest park, Fig. 1 is of the holotype. Scale bar = 10 μm.

FIGURES 10–18: Urosolenia yalongii, SEM. 10. Frustule external view showing the whole valve and two extensions, scale bar = 5 μm. 11. Girdle bands. Middle of the girdle view, showing the external and internal view of the areolae, imbrication line and bands connection internally (black arrow), scale bar = 5 μm. 12. External view of bands and extension, scale bar = 5μm. 13. External view of valve, showing the elongate poroids (black arrow), scale bar = 4 μm. 14–16. Magnification of the extension end with 3–4 teeth, Fig. 14: scale bar = 500 nm, Figs 15,16: scale bar = 400 nm. 17. External view of valve and bands, showing the round poroid on the bands (black arrow), scale bar = 5 μm. 18. Magnification of the extension end with 3–4 teeth, scale bar = 400 nm.